1. Field of the Invention
The present invention relates to an additive for oils that imparts wear resistance properties or friction resistance properties to oils such as lubricant base oils or fuel oils.
2. Description of the Related Art
In recent years, the rapid growth of industry and the increase in market penetration of automobiles and electrical appliances in China, India and Southeast Asia, or the like, have resulted in a dramatic increase in worldwide energy demands. At the same time, environmental impact concerns are beginning to grow worldwide, and all manner of regulations relating to energy conservation, typified by the Kyoto Protocol, are being introduced to alleviate environmental problems such as global warming and acid rain caused by exhaust gases, and the destruction of the ozone layer.
As part of this environmental movement, there are increasingly strong demands for lubricants, and particularly automobile engine oils, that provide lower fuel consumption and longer drain times. At the same time, upper limits have been set for the concentration levels of the metal fraction, phosphorus fraction and sulfur fraction contained within such lubricants (see Non-Patent Documents 1 and 2). Accordingly, lubricants that contain none of these components, and particularly no metal fraction or phosphorus fraction, are now being demanded.
Lubricants are typically produced by adding additives to a lubricant base oil. It is claimed that selecting a lubricant base oil having a low viscosity and superior heat resistance is effective in improving the fuel consumption provided by the lubricant, and known examples of such lubricant base oils include polar base oils such as esters (see Patent Document 1).
Further, lubricants also require all manner of other properties, including wear resistance and friction resistance. Accordingly, as disclosed in Patent Documents 2 to 5, various additives capable of imparting lubricants with wear resistance and friction resistance have been investigated.
[Patent Document 1]    Japanese Laid-Open Patent Application No. 2005-48192
[Patent Document 2]    Japanese Examined Patent Application, Second Publication No. Hei 6-4867
[Patent Document 3]    Japanese Patent (Granted) Publication No. 2,563,295
[Patent Document 4]    Published Japanese translation No. Hei 1-501319 of PCT
[Patent Document 5]    Japanese Laid-Open Patent Application No. 2004-262964    [Non-Patent Document 1] “Journal of Economic Maintenance Tribology”, July 2005 edition, page 7    [Non-Patent Document 2] “Monthly Tribology”, December 2005 edition, page 36